He says the prime minister and Scott Morrison should instead deal with the real problems of house affordability, such as reining in housing tax concessions.

He dismissed reports suggesting the May 9 budget will announce the unlocking of government-owned land for new housing, including defence land in his own seat of Maribyrnong, saying they had been around for six or seven years.

Key crossbench senator David Leyonhjelm questioned why the government had made housing affordability its problem saying the issue had erupted into open warfare on its frontbench last week.

Ministers were openly arguing for and against allowing young people to tap into their superannuation to help build a home deposit, which former Liberal John Hewson described as an "embarrassing free-for-all".

Mr Morrison has made tackling housing affordability a key plank of his second budget.

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But other than flagging a mechanism to encourage the private sector to invest in cheaper community housing, there are question marks about what else he can do to counter rampant house prices in Sydney and Melbourne.

Mr Morrison has ruled out curbing tax concessions that favour housing investors, such as negative gearing, which Labor wants to limit to new properties.

"Why the hell is there a debate at all concerning the federal government?" Senator Leyonhjelm asked on Sky News.

"The levers that the federal government has at its disposal really aren't all that useful in terms of housing affordability."

Issues like housing supply, stamp duty and land tax were a state issue, the Liberal Democratic senator said.

Dr Hewson said it was bad politics to raise expectations beyond what you could deliver.

"Expectations are now running pretty strongly that there is going to be a fairly quick silver bullet, instantaneous-type solution," he told Sky News.

Former Labor minister Craig Emerson agreed.

"They have erected a very large hurdle .... which they will not be able to jump, they'll fall at the first one," Dr Emerson said.

Dr Hewson said Mr Turnbull must impose some discipline to end the government's embarrassing free-for-all on tackling housing affordability.

"My solution (while leader), and it may not be transferable, is to give everybody a job, make them feel important in the policy development process," he said.

"Kept them so damn busy they didn't have time to do all this stuff, and the ones you didn't like you sent them off overseas."